If you’ve read the previous blog entry, you’ll know about my cockpit drain dramas. The epoxy resin kicked as planned and the through-hulls are now part of the hull. I see no reason why anyone would ever have to remove them, so don’t bother telling me I should have bedded them in sealant instead. I made two backing plates from ¼” fiberglass sheet, and bonded them to the inside of the hull with a slurry of epoxy resin and colloidal silica to provide a level base.

The through-hulls were still a little too long to let the seacock flanges rest hard against the base plates before the all the thread was taken up, so I had to find a pair of 1” spacers. I used some spare half-inch UHWMPE – ultra high molecular weight polyethylene – sheet to make them. I don’t believe in using wood or ply for backing plates below the waterline, because it will eventually rot. McMaster Carr sells UHMWPE in assorted sizes and thicknesses. It doesn’t absorb moisture, is resistant to just about anything and will never deteriorate. It’s also dead easy to work. I ran a bead of polysulfide caulk around each side of the spacers, although I probably didn’t need to.

Following Forespar’s instructions, I coated the seacock thread with pipe sealant (you can use tape if you’d rather) and then smeared more polysulfide around the base. My wife screwed them on to the through-hulls – hand tight is enough – and then coaxed the new drain hoses into place. Job done – and what a relief to know that those horrible old gate valves and hoses were gone.

There was a slight moment of panic after the boat was launched. I’d just started the engine and was letting it warm up when I noticed a stream of water making its way from the engine compartment into the bilge sump. Aargh! Were the new seacocks leaking? No, thankfully. I traced the leak to an engine block drain cock that I’d forgotten to shut off after winterizing the engine last fall. Phew…

First, though, there had been another moment of panic, when I noticed that there was no cooling water exiting the exhaust. What could be wrong? I’d just replaced a kinked section of intake hose, and I’d also replaced the impeller. First things first: I ripped the hose off the inlet seacock, and was rewarded with a spout of water. Good - no through-hull blockage. Then I checked out the raw-water pump, and immediately noticed that its drive belt was hanging loose. I had also replaced that – along with the alternator belt – a week earlier. It seemed I had been in such a hurry that I had neglected to feed the belt over the engine pulley before adjusting the tension. When the engine started, the belt merely slipped instead of spinning the pump.

That too was easily fixed, but the lesson is just as valid: don’t rush your maintenance chores, and double-check everything before you launch your boat.

The old and the new. The original-equipment gate valves were in bad shape, and I had to take a Sawzall to the through-hulls.

I used WEST SYSTEM G-Flex epoxy, slightly thickened with colloidal silica, to bond the through-hull to the hull. You must never use microballoons to thicken epoxy used below the waterline, as they are not water-resistant.

I made two fiberglass backing plates and bonded them with epoxy resin to the inside of the hull, bringing the thickness of the laminate to over 1”.

I had to make two spacers per through-hull out of half-inch UMHWPE, and smeared them with 3M 4200 sealant.

We smeared the threads of the Marelon seacock with pipe sealant -- you can use tape instead if you prefer.